1. Field of the Invention
The present invention relates to a method and an apparatus for machine translation for translating a document in a first language into a document in a second language.
2. Description of the Background Art
Lately, machine translation apparatus for carrying out automatic translation has attracted much attention. In this apparatus, it is possible to record an original document and a translated document in sentence by sentence correspondence, and to modify the translated document in this sentence by sentence correspondence. Also, such a machine translation apparatus is often employed as a translation assistance system in which the translated document obtained by the machine translation apparatus is inspected and modified if necessary by the human translator.
In such machine translation, there appear situations in which sentences similar to other sentences already translated are encountered, which become especially frequent in a case dealing with a large amount of documents.
However, in a conventional machine translation apparatus and method, the translation is carried out for each sentence independently, so that similar inspections and the modifications have to be repeated for each of the similar sentences. Thus, with regard to similar sentences occurring repeatedly, the conventional machine translation apparatus and method have been rather inefficient.
The conventional machine translation apparatus and method are also associated with the following problems related to the one just mentioned.
Namely, a dictionary to be utilized in carrying out the translation, which stores words and expressions in a first language in correspondence with appropriate translations in a second language of these words and expressions, is usually made to be modifiable by an operator so as to be able to improve the effectiveness of the translation. Now, in a conventional machine translation apparatus, when such a dictionary is modified during the course of translation of certain data comprising plurality of documents, those documents which have already been translated at the time of the modification of that dictionary need to be translated all over again using the modified dictionary, in order to maintain consistency within the data. This re-translation conventionally is done for the entire document regardless of the extent of the modification, so that in effect, when the modifications are relatively small in number, exactly the same translation have to be re-performed for a large portion of the entire documents. This obviously made a conventional machine translation apparatus quite inefficient in situations like these.
Another situation similar to this one arises as follows. That is, the machine translation apparatus often employs more than one dictionary, such as a general purpose dictionary and various specialized terminology dictionaries, from which appropriate ones are selected for different documents. Now, conventionally, when such use of more than one dictionaries is involved, it was not possible to know which one of the dictionaries had been used in translating each word or expression of the document, so that in inspecting the translation it has often been difficult for an operator to decide whether modification is necessary since the operator is usually not required to be thoroughly acquainted with the specialized terminologies. Moreover, as the number of documents increases, there appear situations in which similar sentences are to be translated with different choices of specialized terminology dictionaries as they belong to different technical fields. In such a case, entire sentences have to be re-translated a number of times using a different specialized terminology dictionary, even when a large portion of these sentences are identical when translated using the general purpose dictionary. Again, this made the conventional machine translation apparatus quite inefficient.